TGF-ß-p-STAT1-LAIR2 axis has a "self-rescue" role for exhausted CD8+ T cells in hepatocellular carcinoma.

ABSTRACT

BACKGROUND: TGF-ß is related to the function of T cells in the tumor microenvironment. However, the characteristics of TGF-ß affecting the function of CD8+ T cells in hepatocellular carcinoma (HCC) have not been clearly resolved. METHODS: In this study, flow cytometry, mass cytometry, immunohistochemistry, RNA-seq, single-cell RNA-seq, assay for transposase-accessible chromatin with high throughput sequencing, chromatin immunoprecipitation, and dual-luciferase reporter gene assay were used to study the regulatory effect and molecular mechanism of TGF-ß on HCC infiltrating CD8+ T cells. RESULTS: Here, we demonstrated that the overall effect of TGF-ß on CD8+ T cells in HCC was to activate p-p38 to induce exhaustion, but it also initiated cell-intrinsic resistance mechanisms 1) TGF-ß upregulated the levels of p-STAT1 (S727) and promoted LAIR2 secretion; 2) the TGF-ß-p-STAT1-LAIR2 axis relieved CD8+ T cells from exhaustion, which we called "self-rescue"; 3) this "self-rescue" behavior showed time and dose limitations on TGF-ß stimulation, which was easily masked by stronger inhibitory signals; 4) the function of CD8+ T cells was improved by using TAK-981 to amplify "self-rescue" signal. CONCLUSION: Our study describes a "self-rescue" mechanism of CD8+ T cells in HCC against exhaustion and the good effects from amplifying this signal.